Today's vehicles use control units for internal combustion engines, which include monitoring according to the so-called “Standardized E-Gas [FOOT drive-by-wire system or e-gas] Monitoring Concept for Gasoline and Diesel Engine Control Units”. The monitoring is intended to prevent undesired vehicle behavior.
The principle of functional monitoring, in this instance, is as follows: An admissible torque is calculated which takes into account a plurality of influence variables, such as the driver's command, internal friction torque or external users. On the other hand, an actual torque is calculated from current engine variables. For this purpose, the throttle valve angle, the intake manifold pressure, the injection times, the injection pressures and the injection angles, among others, may be taken into account.
The aim of the functional monitoring is to hold the actual torque to below the admissible torque, in order to prevent undesired acceleration. Demands are, therefore, made on a monitoring concept, among other things, the observance of a certain error reaction time, so that faulty vehicle reactions, such as an undesired acceleration, remain manageable. This means that an error has to be detected and debounced within a certain time. After an unequivocal error detection, the vehicle must then be brought into a safe state.
Because of reading back actual values, the engine control unit requires a certain time for this: Thus, the actual torque must first build up, for example, and then corresponding actuator values may be read back. For Otto and Diesel engines this admitted error reaction time generally amounts to 500 ms. For the monitoring of driving dynamics longitudinally to the travel direction, this error reaction time is generally sufficient. The E-gas monitoring concept was appropriately adapted to electric motors.
Increasingly, hybrid vehicles are also produced, which combine internal combustion engines and electric motors. In hybrid vehicles, the engine control unit of the internal combustion engine is frequently used for determining a torque distribution between the internal combustion engine and the electric motor. In this case, the setpoint and actual torque of the electric motor have to be integrated into the functional monitoring. This takes place according to the same principle as with only an internal combustion engine: From the overall setpoint torque, the engine control unit calculates the setpoint torque and the controlled variables for the internal combustion engine and the setpoint torque for the electric motor. The actual values are then read back in order to calculate the actual torque. In this instance, the control unit for the electric motor calculates from its actuator values the actual torque of the electric motor and sends this to the engine control unit of the internal combustion engine.
In recent times, vehicles have also been developed which use electric motors for implementing single-wheel drives, both on the front and the rear axle. If the electric motors on one axle supply different torques for the right and the left wheel, a torque is created that is transverse to the travel direction. Torque requirements for this may originate, for example, from an ESP control unit for regulating the vehicle stability, and may be routed via the engine control unit.
This transverse torque may be used to support the steering, and consequently the vehicle behaves in a more agile manner in curves. However, erroneously supplied torques may now lead to undesired transverse dynamics, that is, to undesired directional change all the way up to the occurrence of skidding. On the one hand, this is classified as being more dangerous than an undesired longitudinal dynamics, and on the other hand, errors in the field of transverse dynamics have to be detected more quickly, since driving experiments have shown that such errors are able to lead to skidding even after times below 100 ms, for instance.
It would therefore be desirable to indicate a possibility of reducing an error reaction time for specifications which refer to the transverse dynamics of a vehicle as compared to the related art.